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@niintatca lgattini @ffirrQ Letters Patent No. 80,894, dated .August'll, 1868.

IMPROVEMENT 1N OLAMPS.

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TO ALL WHOM' I'I MAIZ CON CERN: x

Be it known that I, ANnRW ANDERSON, of Madison, in the county of Dane,and State of Wisconsin, have` made new and useful ImprovementsinSelf-Adjusting Clamps; and I do hereby'r declare the following to be afull, clear, and ekact description .of thc nature, construction, andoperation of the same, sufficient to enable one .skilled in the art towhich it appertains to construct and use the same, reference bein-g hadto the accompanying Vbeing provided with bosses projecting downwards, z'z', and its centre with another, j, iig.v 3.

drawings, which are made part of this specification, and in which-Figure 1 is a perspective elevation of the machine. Figure 2 is asidesectional View of the same. Figure 3 is any end sectional view. V p Y YThe object of this invention is to provide' a clamp which will, at onevoperation or movement of the hand, ,attach itself rmly to' josts inbuildings, ribs of ships,&c., and also press to its place the plank orflooringl which is beingrlaid, and hold it securely until it is spikedor nailed.

It consists of uniting together a pair of jaws, A, rigs; 1 and 3, neartheir lower end, by means of hinges, toggle-joints, or other flexibledevices, the upper ends of said jawsv being made circular, as yat B,iig. 2, and cam-shaped', asy shown at C C, iig. 1, the cams commencingto curve outward at the inner surface of the jaws, at or near d clg. 1,and widening or separating from each other as the cam-ledge approachesthe edge of the jaws fat C C, iig. 1. I

It further consists in. the application of a lever, E,`igs. 1, 2, andS,in sucha manner as to cause, by

swinginglthe upper end of the lever forward and backward, an opening andclosing movement of each end of the jaws, and to force forward andbackward by the same movement a plunger, F,figs.' 1 and 2.r

' The plunger is a straight piece of iron'or`wood,'provided with a'cross-piece at its outer end, and slotted uponl each edge, (O, iig. 2,)near the cross-piece. It is attached to the lever at P,ig. 2, and slidesupon the two .pins i', 7;, g. 3,projectingpfrom the inner face of thejaws. The lever is suspendedbetwcen'the jaws by a pin or bolt, iig. 2,at a point which is the centre of an are of a circle, shown at thetop'ol the jaws in fig. 2.

-At a point upon the lever even with the top of the jaws, ayoke, Hj H,iig. is secured to thelever, its ends These bosses, enclosing thecam-ledgeoutand inside, serve, to control the jaws, and cause the motionof the same to and from 'each other at their ends, when the lever isoperated forward'and backward.

The lower ends, K, g. 2, of the jaws are provided with spikes, L L L,iig. 2, which penetrate the joist M,

iig. 1, when the lever'is pressed back to an upright position, (as iniig. 1,)' and prevents the jaws from slipping whenthe plunger is broughtagainst the doorboard or plank to be operated upon.

To operate the machine, place it astride the joist M, figs. 1 and 3,with the handle or lever in the ,position shown in iig. 2,-and thccrosslpiece of the plunger close tozthe hoard to be operated upon; thenpress the handle backward nearly dr quitel into the position, shown iniig. 1, as may be found necessary to bring the board to a tight jointwhere Vitis' to be nailed.

l VTo remove the clamp, pull the handle forward, whenl it will releasethe board from pressure and itself from the joist, and may bc`1en1oved.I

A pawl orhand may b'e attached to the handle in such manner as to catchinto teeth orcogs cut into the periphery of. the cams, and holdpthchandle in the position to which it -has been brought (in forcing thehoard toa joint) while nailing.,V j Y i T heclamp may beset topanythickness of joist bymoving the nuts S S, igsfl, 2, and 3.

Having described 'my invention, what I claim asnew, and desire to secureby Letters Patent, isf- The combination of the cams C G, the jaws A A,the lever E,-the yoke H H, and the plunger F, all c.on-

structed, arranged, andoperating asand for thelpurposcs herein setforth.

ANDREW ANDERSON.

Witnesses K. F; Fnnrscnnn, IO. E. Woonunr.

